In the data storage system manufacturing industry, various methods have been employed to minimize the detrimental influence of strong external rotational shock forces on the operation of the sensitive components comprising a data storage system. A typical data storage system includes one or more data storage disks coaxially mounted on a hub of a spindle motor. The spindle motor rotates the disks at speeds typically on the order of several thousand revolutions-per-minute. Digital information is typically written to and read from the data storage disks by one or more magnetic transducer heads, or read/write heads, which are passed over the surfaces of the rotating data storage disks.
An actuator typically includes a plurality of outwardly extending actuator arms adapted to interleave one or more magnetic transducer heads mounted thereon into and out of the stack of data storage disks. During periods of data storage system inactivity, the actuator is often restrained in a predetermined parked position by a passive locking or parking mechanism, such as a parking ramp apparatus, for example. The magnetic transducer heads are usually parked beyond the outer diameter of the data storage disks or over a dedicated portion of the disk, often termed a landing zone, situated away from the data storage portions of the disk.
Mishandling of either the data storage system or a computer system into which the data storage system is installed often results in displacement of the actuator from its parked position. Such direct and indirect mishandling often subjects the sensitive internal components of the data storage system to significantly large rotational shock forces. The rotatably mounted actuator is generally susceptible to rotational forces and often rotates out of the parked position when the data storage system is subjected to a sufficiently strong rotational shock force. Unrestrained movement of the actuator typically results in varying degrees of permanent damage to the sensitive surfaces of the data storage disks and to the magnetic transducer heads. A damaged region of the disk is generally unusable for subsequent storing of data. Also, if the disk is damaged, any data stored at the damaged location may be lost.
Various methods and apparatus have been developed to reduce the potentially catastrophic results of unrestrained actuator rotation out of the parked position during periods of data storage system inactivity. One conventional technique employs an apparatus that passively latches the actuator in a parked position until the external rotational shock forces applied to the data storage system are dissipated. A known method for minimizing unintended rotation of the actuator is illustrated in FIG. 1. An inertial latch 48 is typically mounted for rotation about a pivot axis 56, and includes a weighted portion 50 and hook portion 54. In response to a sufficiently strong rotational shock force applied to the data storage system 20, the hook portion 54 of the inertial latch 48 typically rotates about the pivot axis 56 and engages a receiving hook 52 protruding from the actuator 30. A biasing mechanism 55 is generally employed to return the inertial latch 48 to its original position. It is noted that the data storage system 20 illustrated in FIG. 1 is generally representative of a standard form factor data storage system having ample space available on the base 22 to accommodate the dimensions and rotation of a prior art inertial latch 48.
A trend has developed in the data storage system manufacturing community to miniaturize the chassis or housing of a data storage system to a size suitable for incorporation into miniature personal computers, such as lap-top computers, for example. Various industry standards have emerged that specify the external housing dimensions of small and very small form factor data storage systems. One such recognized family of industry standards is the PCMCIA (Personal Computer Memory Card Industry Association) family of standards, which specifies both the dimensions for the data storage system housing and the protocol for communicating control and data signals between the data storage system and a host computer system coupled thereto. Recently, four families or types of PCMCIA device specifications have emerged. By way of example, a Type-I PCMCIA data storage system must be fully contained within a housing having a maximum height dimension of 3.3 millimeters (mm). By way of further example, a Type-II PCMCIA device housing must not exceed a maximum height of 5.0 mm in accordance with the PCMCIA specification. A maximum height of 10.5 mm is specified for the housing of Type-III PCMCIA devices, and Type-IV devices are characterized as having a maximum housing height dimension in excess of 10.5 mm.
It is anticipated that the industry trend of continued miniaturization of data storage systems will eventually result in the production of systems complying with the Type-II PCMCIA specification. Such Type-II PCMCIA data storage systems will likely have external housing dimensions of approximately 54 mm.times.86 mm.times.5 mm, and include a data storage disk having a diameter of approximately 45 mm and a width dimension similar to that of a standard credit card. It will likely be desirable to employ an inertial latch assembly within such small and very small form factor data storage systems, such as Type-II PCMCIA data storage systems. Those skilled in the art, however, will appreciate the difficulties associated with employing an inertial latch mechanism suitable for use within these very small form factor (VSFF) data storage systems. The maximum allowable housing dimensions imposed by the Type-II PCMCIA specification, for example, necessarily results in a highly compact packaging configuration within the data storage system housing, with minimal clearance and tolerances afforded between adjacent components.
Employment of a prior art inertial latch 48, such as the one depicted in FIG. 1, within the compact environment of a VSFF data storage system is generally considered problematic for a variety of reasons. Conventional inertial latches 48 generally occupy an appreciable amount of space on the housing base 22 of a data storage system 20 in order to permit the weighted portion 50 and elongated hook end 54 to freely rotate into and out of engagement with the actuator 30 unimpeded by other components mounted on the housing base 22. Also, prior art inertial latches 48 are typically situated within the housing 20 far away from the sensitive data storage disks 24 to avoid any possible contact therewith. These and other characteristics of prior art inertial latches generally represent significant limitations in the development and optimization of the component layout within the limited space of a VSFF data storage system.
Further, as illustrated in FIG. 2, conventional inertial latches 48 are typically designed to operate within a plane 47 of rotation (X-Y plane) substantially parallel to a plane defined by the rotation of the data storage disk 24. A prior art inertial latch 48 is generally designed to sweep through a predetermined arc within the X-Y plane 47 when activated. Such conventional inertial latch 48 designs are generally directed exclusively to operation within this X-Y plane of rotation 47, with little or no consideration given to the advantages and disadvantages associated with operation in the vertical Z direction 49 with respect to the X-Y plane 47.
There is a desire within the data storage system manufacturing community to minimize potential damage to the sensitive internal components of a miniature data storage system when the system is subjected to strong rotational shock forces. There exists a further desire to incorporate the advantageous attributes of an inertial latch within the compact packaging configurations of small and very small form factor data storage systems produced in a high-volume, cost-sensitive manufacturing environment. The present invention fulfills these and other needs.